A primary purpose of the cardiovascular system is to sustain a normal flow of blood necessary to furnish oxygen and nutrients to the body's cells. The heart functions as the pump of the cardiovascular system, and it can change the strength of its contraction and the rate at which the heart contracts to regulate the flow of blood. If there is an abnormality in the heart's rate and in its rhythm, as in cardiac arrhythmias as evidenced by a loss of rhythm, or an irregularity of the heart beat, the biological consequence is a disruption of the cardiac output. This condition can lead to decreased tissue and organ perfusion. The atrial and ventricular arrhythmias can produce symptoms, induce heart failure, and lead to lethal arrhythmias such as asystole and ventricular fibrillation.
Recently, as reported in Clinical Pharmacokinetics. Vol. 14, pp 141-147, (1988), the drug encainide, chemically identified as (.+-.)-2'-[2-(1-methyl-2-piperidyl)ethyl]-p-anisanilide, and its therapeutically acceptable salts, became available to the medical profession for the prevention and the treatment of cardiac arrhythmias. The drug encainide is indicated for the treatment of ventricular premature complexes and for other ventricular arrhythmias. In most patients on encainide therapy, encainide undergoes hepatic biotransformation to its active metabolites 0-desmethyl encainide and 3-methoxy-0-desmethyl encainide as reported in Am. J. Cardiol. Vol. 58, 4C, (1986). The drug encainide in possessing electrophysiological effects shows intracardiac conduction and it is a potent sodium-channel blockers. In the reported study the drug encainide was administered as a tablet in an uncontrolled dose that was subjected to the changing adverse environment of the gastrointestinal tract.
In light of the above presentation, it will be appreciated by those versed in the dispensing art to which this invention pertains that a pressing need exists for a delivery dispenser which is a rate controlled dosage form that can deliver the valuable drug encainide to a patient in need of cardiac therapy. The need exists also for an oral dosage form that can deliver encainide at a controlled rate in a substantially constant dose per unit time over a prolonged period of time for encainide's beneficial pharmacological and physiological effects substantially independent of the changing environment of the gastrointestinal tract. Those versed in the dispensing art well appreciate that such a novel and unique delivery dispenser that can administer encainide in a rate controlled dose over time, and simultaneously provide cardiac therapy, would represent an advancement and valuable contribution to the dispensing art.